1. Field
One or more embodiments described herein relate to inspecting substrates.
2. Description of the Related Art
A semiconductor device may be manufactured using a fabrication process (FAB) for forming electrical circuits on a substrate. An electrical die sorting (EDS) process may then be used for testing electrical characteristics of the device. A package assembling process encapsulates the device with an epoxy resin.
Various unit processes may be used for the FAB process. These unit processes include: a deposition process for forming a thin layer on the substrate, a chemical mechanical polishing (CMP) process for polishing the thin layer for planarization, a photolithography process for forming a photoresist pattern on the thin layer, an etching process for forming the thin layer into a pattern having electrical characteristics using the photoresist pattern, an ion implantation process for implanting ions into regions of the substrate, a cleaning process for cleaning impurities from the substrate, and an inspection process for inspecting defects in the thin layer or patterns on the surface of the substrate.
The inspection process may be performed because defects have been shown to degrade operating characteristics of the semiconductor device. Defects may also reduce the production efficiency, and thereby limit the competitiveness of the manufacturing company. Examples of defects include scratches, particles, and unremoved portions of material layers formed on the surface of the semiconductor substrate.
Defects which are not detected during inspection may cause the semiconductor device to malfunction or be inoperative. Examples of devices used to inspect semiconductor devices include electron microscopes (SEMs), transmission electron microscopes (TEMs), and secondary ion mass spectrometry (SIMS) devices which use ion beams. Other devices include surface test devices which use laser beams for inspection.
These and other inspection devices have proven inadequate in a number of ways. For example, these devices demonstrate poor signal-to-noise ratio which limits detection performance. Other devices have other performance defects which cause defects to go undetected.